Underground Aliens (S02E04)

What if aliens had a hand in shaping human civilization? Could concealed passages and underground chambers across the globe hold the key? In Ecuador, tales suggest a cavern might house metallic volumes filled with advanced alien knowledge. In Turkey, an ancient subterranean metropolis raises questions: Was it constructed with extraterrestrial assistance or as a safe haven from an alien threat? Ongoing speculation surrounds a covert U.S. military installation in a New Mexico mesa rumored to collaborate with aliens, while Native American folklore speaks of mysterious beings from within the Earth. Recent archaeological finds in the Yucatan could hint at an alien influence in our past.